So I had a melt down in my r69s, lean carb + advanced timing + who knows what. Got the new pistons from vech, bores done, so I'm looking at top end stuff now. The chamber looks ok, scraped a little melted piston from the inside, but it should be ok. I'm going to pit some pics, so if you all think things are toast, let me know. Thanks!
Here's the other valve.
Here it is
Cleaned up just a little...
Can't tell.
Look straight at the side of the head of the valve and measure the margin (width of the edge). I don't know the spec but it ought to be a clean square edge.
Then, look at that exhaust seat. I note the intake remains shiny as expected but the exhust seat appears to be a little knarly but I can't tell for sure.
Paul Glaves - "Big Bend", Texas U.S.A
"The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
http://www.bigbend.net/users/glaves
Here's a better pic from a "real" camera of the valve seat.
I'm mostly concerned about the crap below the valve guide area and above the seat on both valves. I'm assuming that it could come off fairly easily, but it may require a little "persuasion". As long as it's below the valve guide, should there be a problem?
Thanks!
Were it my bike I'd at a minimum lap the valves to the seats. Depending upon the results the seats may need to be re-cut and the valve re-ground.
I agree. Post#6 clearly shows some seat erosion at the 6:00 to 7:00 position in the photo but post#7 shows what appears to be plenty of margin on the valve.Originally Posted by marchyman
Deposits on the stem should not be a problem provided they are below the guide.
Paul Glaves - "Big Bend", Texas U.S.A
"The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
http://www.bigbend.net/users/glaves
Looks are not really that much of a consideration. You have to do some measuring and examination here.
1. if you mount these valves in a valve grinder, or a lathe, by the stems, and turn them slowly, does the face of the valve turn true? Lots of heat can warp a valve. If they are warped, replace them. Forget grinding them. New ones are not that expensive.
2. Due to the lack of lead in gas, the valves all wear on the stem, where they run in the guide.
If the valve passes the test described in #1 above, measure the stems, in various places, down the length. Is it consistent? If not, replace them. How does it fit the guide? Is it time for new guides?
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